Aircraft applicable current imbalance detection and circuit interrupter and packaging thereof

ABSTRACT

The aircraft applicable current imbalance detection and circuit interrupter interrupts an electrical circuit when a current imbalance is sensed. The current imbalance detection and circuit interrupter includes a housing, power supplies, a sensor for sensing a current imbalance at the line side of the electrical circuit, a logic controller and a power controller. In a preferred embodiment, the invention can also include a fault indicator, a press to test switch and a reset switch. The power supplies provide power to the sensor, logic controller, and the power controller. The logic controller receives input from the sensor and the relay control signal, and the power controller receives input from the logic controller, and interrupts power to the load side of the electrical circuit when the sensor senses a current imbalance. Power interruption due to a sensed current imbalance is maintained until the line side power source is cycled. The circuit interrupter is preferably autonomous, requiring no additional signals, inputs, wiring or sources of power. The current imbalance detection and circuit interrupter is packaged in a configuration integral with the power controller, thus easing retrofit with the improved aircraft applicable current imbalance detection and circuit interrupter.

RELATED APPLICATIONS

[0001] This is a continuation in part of Ser. No. 09/775,337, filed Feb.1, 2001.

BACKGROUND OF THE INVENTION

[0002] This invention relates generally to electrical control systems,and more specifically to an aircraft electrical control system whichdisconnects power to a load when a current imbalance is sensed.

[0003] In the electromechanical arts, current imbalances are indicativeof serious problems that can lead to disastrous results, such as arcingwithin fuel pumps. Since fuel pumps are often housed within a fuelvessel to directly pump fuel out of the vessel, arcing within a fuelpump can lead to an explosion of fuel-air mixture and a subsequentbreach of the fuel vessel, which can be catastrophic. In light of theseriousness of such an event, a device or methodology is needed whichcan suppress this type of arcing, as well as other associated problems.Presently, a common type of circuit protection device being utilized inaircraft is a thermal circuit breaker. However, arcing typically doesnot cause thermal circuit breakers to activate. Thus, there has been along-felt need for the function of current imbalance detection in anaircraft. One very important form of current imbalance is a ground faultin which current is flowing between a circuit or electrical device toground, when such current flow is not desired. In the prior art, groundfault detection has been addressed by a separate ground faultinterruption unit. However, such prior art systems have had limitations,including the necessity of rewiring the aircraft. In addition to therequirement to rewire the aircraft, additional space had to be found toaccommodate the ground fault interruption system.

[0004] One currently available ground fault interruption unit made byAutronics (model 2326-1) has been used in large commercial aircraft forthe purpose of ground fault protection for fuel pumps. The Autronicsunit detects a ground fault and outputs a signal indicative of a faultby use of a current transformer and acts by removing power to the fuelpump control relay.

[0005] There exists a need for an improved circuit protection device foraircraft. It would further be desirable for the circuit protectiondevice to be included within an existing device in the aircraft, or tobe packaged with an existing device, sharing the same connections toexisting electrical circuits, since space for avionics is limited in anyaircraft and adding wiring to accommodate a new device is verydifficult. The present invention addresses these and other concerns.

SUMMARY OF THE INVENTION

[0006] Prior art systems for ground fault detection are helpful toreduce arcing in aircraft electrical systems, including aircraft fuelpumps. This issue has become a major concern of the Federal AviationAdministration and recent studies have promulgated a variety of studiesand regulations in an attempt to prevent fuel tank ignition. One recentconference on fuel tank ignition prevention hosted by the FAA on the20^(th) and 21^(st) of June 2001 at the SEATAC Airport Hilton was givenin order to better understand the provisions SFAR No. 88 and relatedcertification procedures and airworthiness standards for transportcategory aircraft. A copy of the materials handed out and discussed atthat meeting is attached hereto as Appendix A and incorporated herein byreference. Also attached as Appendix B is a copy of the Federal Registerof Monday, May 7, 2001 relating to SFAR No. 88, “Fuel Tank System FaultTolerance Evaluation Requirements and Related Airworthiness andCertification Standard”. These materials and this conference emphasizedthe importance of detecting ground faults and operating on the circuitto prevent, to the largest extent possible, arcing within fuel pumps andthe like that may be exposed to flammable materials.

[0007] In addition to the Autronics Corporation Model No. 2326-1 seriesground fault current detector previously discussed (and attached heretoas Appendix C), there also exists a ground fault detection system soldby PRIMEX Aerospace Company as Part No. 437, 437. A brochure for thePRIMEX system is attached as Appendix D. The PRIMEX system uses acurrent transformer to detect ground fault currents in three phase 400Hertz motors. However, these prior art systems has serious limitationsif they are to be broadly applied to aircraft, either as originalequipment or retrofit, and they require separate wiring and space inaddition to the currently existing equipment. The present inventionoffers many operational and functional advantages, in that it fits intothe space available on the panel for the existing relays, utilizes thepower of the system it is monitoring to operate, and is functionallyfaster and more efficient in detecting a ground fault and removing powerfrom the system being monitored.

[0008] The present invention is a current imbalance detection andcircuit interrupter particularly attractive for use in aircraft, forprotecting a circuit having a line side and a load side. In a currentlypreferred embodiment, the present invention incorporates the currentimbalance detection and circuit interrupter within the existing aircraftpower control relay package. For example, in a fuel system application,the current imbalance detection and circuit interrupter is incorporatedwithin the fuel pump control relay package. Therefore, the invention canbe retrofit to existing aircraft, or can be utilized in newlyconstructed aircraft and new aircraft designs already incorporating therelay system. The current imbalance detection and fault circuitinterrupter includes a housing, a power supply, a circuit to bemonitored, a sensor, a logic controller, and a power controller (forexample: relay, contactor, solid state relay, etc.). In a presentlypreferred embodiment, the invention can also include a fault indicator,a press to test switch and a reset switch. The power supply isconfigured to provide power to the sensor, logic controller and thepower controller. The sensor is configured to sense a current imbalancein the circuit being monitored. In one presently preferred embodiment,the sensor to monitor current imbalance is a Hall effect sensor. Thelogic controller is configured to monitor a relay control input signaland to process inputs from the sensor.

[0009] In a presently preferred embodiment, the logic controllercompares the sensor signal with predetermined limits representingacceptable operation and outputs a signal representing a circuit currentimbalance when the sensor signal is outside the acceptable limits. Thepower controller is configured to receive input from the logiccontroller and remove power to the load side of the circuit when acurrent imbalance is sensed. In a presently preferred embodiment, thepower removal from the load side of the circuit due to a sensed currentimbalance is maintained until the power source to the current imbalancedetection and circuit interrupter is cycled. In another presentlypreferred embodiment, power removal is maintained until a reset switchis activated. In a presently preferred embodiment, the fault indicatorprovides an indication of whether a current imbalance condition hasoccurred. A press to test switch may be included to check the operationof the unit during maintenance. In a presently preferred embodiment, thefault reset switch is used to reset the fault indicator.

[0010] The present invention also provides for a method for interruptingan electrical circuit for an electrical load, the electrical circuithaving a line side and a load side with a ground fault. In summary, themethod comprises providing a supply of power, continually monitoring andsensing the line side of the circuit for a current imbalance,continually monitoring the relay control input, receiving input from alogic controller and interrupting the relay control input signal when acurrent imbalance is sensed, and enabling the fault indicator. In onepresently preferred aspect of the method, interrupting of the circuitwhen a current imbalance is sensed is maintained until the power sourceis cycled. Typically, the load being supplied with the current beingmonitored is a motor. In another preferred aspect, the current imbalancedetection and circuit interrupter requires no additional signals,inputs, wiring, or sources of power, but takes its power from thecircuit being monitored. In one presently preferred use of the method,the load side of the circuit is connected to a fuel pump, and arcing isterminated within the fuel pump.

[0011] In one presently preferred embodiment, the present invention isconfigured to perform ground fault detection and circuit interruption(GFI) and provides important advantages over prior art systems. Sincethe GFI system of the invention is packaged in the same envelope as anexisting relay system, it can be readily retrofit to existing aircraft.Since it is easily operated off of either AC or DC circuits, containingits own power supply powered by the circuit being monitored, it can beused on either AC or DC wired aircraft without further change orrewiring in the aircraft. Furthermore, since the GFI system of theinvention operates directly on and is part of the circuit beingmonitored, it avoids a major issue with prior art systems, which had tobe separately connected to the circuit being monitored. Anothersubstantial advantage to the present invention is that it more quicklyremoves power from the circuit with a fault, since sensing and controlis at a single location, thus providing in situ sensing and control.

[0012] Most aircraft presently in service utilize circuit breakers withthe limitations previously discussed. While the electronic andelectromechanical aspects of the present invention impart additionalprotection to the protection provided by such circuit breakers, it wouldbe desirable to be able to package the invention in a form which wouldallow ease of retrofit to existing aircraft, newly constructed and newaircraft designs, thus bringing the benefits of the invention to a widerrange of applications. Accordingly, in a further presently preferredaspect of the invention, the electronic and electromechanical elementsof the current imbalance detection and circuit interrupter are housedwithin a housing which has a similar form factor to prior art powercontrollers. The invention connects with the circuit to be monitored andcontrolled, through the existing power controller electrical connector,and it draws power from the circuit to be controlled. While there arenumerous form factors which can impart additional protection to theprotection provided by such circuit breakers, the most desirable formfactors are related to the power controllers used in aircraft.

[0013] Other features and advantages of the present invention willbecome apparent from the following detailed description taken inconjunction with the accompanying drawings which illustrate, by way ofexample, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 illustrates a block diagram of a first embodiment of acontrol system of the present invention adapted for a Boeing 757aircraft, for interrupting the circuit when a current imbalance issensed;

[0015]FIG. 2 illustrates a detailed view of the power supply portion ofthe control system shown in FIG. 1;

[0016]FIG. 3 illustrates a detailed view of the logic controller portionof the control system shown in FIG. 1;

[0017]FIG. 4 illustrates a detailed view of a sensor for the controlsystem of FIG. 1;

[0018]FIG. 5 illustrates a block diagram of a second embodiment of acontrol system of the present invention adapted for a Boeing 747aircraft, for interrupting the circuit when a current imbalance issensed;

[0019]FIG. 6 illustrates a detailed view of the power supply portion ofthe control system shown in FIG. 5;

[0020]FIG. 7 illustrates a detailed view of the logic controller portionof the control system shown in FIG. 5;

[0021]FIG. 8 illustrates a detailed view of a sensor for the controlsystem of FIG. 5;

[0022]FIG. 9 illustrates a block diagram of an alternate preferredembodiment of a control system of the present invention adapted forproviding the speed of a DC relay in an AC application for interruptingthe circuit when a current imbalance is sensed;

[0023]FIG. 10 illustrates a detailed view of a preferred embodiment ofone section of the power supply portion of the control system shown inFIG. 9;

[0024]FIG. 11 illustrates a detailed view of a second section of thepower supply portion of the control system shown in FIG. 9;

[0025]FIG. 12 illustrates a detailed view of the preferred logiccontroller portion of the control system shown in FIG. 9;

[0026]FIG. 13 illustrates a detailed view of a sensor for the controlsystem of FIG. 9;

[0027]FIG. 14 is a side elevational view of an aircraft applicablecurrent imbalance detection and circuit interrupter according to thepresent invention;

[0028]FIG. 15 is a rear view of the aircraft applicable currentimbalance detection and circuit interrupter shown in FIG. 14;

[0029]FIG. 16 is a bottom view of the aircraft applicable currentimbalance detection and circuit interrupter shown in FIG. 14;

[0030]FIG. 17 is a side elevational partial cutaway view of the aircraftapplicable current imbalance detection and circuit interrupter shown inFIG. 14;

[0031]FIG. 18 is a sectional view of the aircraft applicable currentimbalance detection and circuit interrupter taken along line 18-18 ofFIG. 17; and

[0032]FIG. 19 is a sectional view of the aircraft applicable currentimbalance detection and circuit interrupter taken along line 19-19 ofFIG. 17.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033]FIG. 1 illustrates a preferred embodiment of a control system 10,adapted for a Boeing 757 aircraft, and FIG. 5 illustrates a preferredembodiment of a control system 10, adapted for a Boeing 747 aircraft,each being constructed in accordance with the present invention fordisconnecting power to a load when a current imbalance is sensed.Referring to FIGS. 1 and 5, the aircraft applicable current imbalancedetection and circuit interrupter 10 of the invention interrupts acircuit 20 having a line side 24 and a load side 26 with a ground fault.The load may be a motor, or any electrical device drawing a load, whereprotection of equipment or personnel is desired. The current imbalancedetection and circuit interrupter of the invention includes a powersupply 30, a sensor 40, a logic controller 50, a power controller 60,and a fault indicator and reset 55. The power supply is configured toprovide power to the logic controller, and the sensor is configured tosense a current imbalance in the line side 20 of the circuit 24, and tooutput a sensor signal to the logic controller. The logic controller isconfigured to receive and process the sensor signal input from thesensor and the relay control input signal, and the power controller isconfigured to receive input from the logic controller and remove powerto the load side of the circuit when a current imbalance is sensed.

[0034]FIGS. 2 and 6 illustrate a detailed view of a preferred embodimentof the power supply, and FIGS. 3 and 7 illustrate a detailed view of apreferred embodiment of the logic controller. Referring to FIGS. 4 and8, showing a sensor for use in the control system of the invention, in apreferred embodiment of the present invention, the sensor, which is anAmploc Pro 5 Hall effect linear current sensor with an output of 233mV/A when operated at 10V. All three line side wires pass through thesensor core. Kirchoff's current law states that the net current in anode is 0. Considering the wye connection point of the load side pumpwinding, the net current in the phase windings, when algebraicallysummed, is 0. If a ground fault exists, that is where the current issupplied through the sensor but does not return through the sensor, thealgebraic sum of the currents in the phase wires would be equal to theground fault current.

[0035] Referring to FIGS. 3 and 7, in a preferred embodiment, the outputof the sensor is approximately one-half of the supply voltage, for nomeasured imbalance. Amplifier U3A amplifies the signal by a factor of10. The gain is set by the ratio of resistors R5 and R3. The 3 db pointis where the reactance of capacitor C4 is equal to the resistance of R5.This occurs at 3386 Hz. Resistors R1, R2, and R4 bias the amplifier andhave been selected so that a maximum value of 1 meg, for resistor R4, isrequired to adjust the amplifier output to mid supply with the sensor atits specified worse case high output. Calibration for the worse case lowoutput of the sensor is easily achieved.

[0036] Amplifiers U3B and U3C, and resistors R6, R7, and R8 are set todetect a current imbalance of 1.5±0.5 Arms. A high output from amplifierU3B or U3C indicates an imbalance is present in excess of the 1.5 Armsthreshold. IC U4A “OR's” the outputs from amplifiers U3B and U3C. Alogic 0 at its output indicates one or the other failure condition ispresent. Simultaneous imbalance inputs can be handled but are physicallynot possible since a positive imbalance cannot exist at the same time asa negative imbalance.

[0037] If a fault condition exists, it passes through IC U5A presentinga logic 1 to the latch comprised of ICs U4B and U4C. A logic 1, at pin5, forces the output pin 4 low, turning transistor Q1 off, which removesthe drive signal to the power control stage. Pin 9, the other input tothe latch, is normally at logic 0. This will cause pin 10 to go high,setting the latch by presenting a logic 1 to pin 6.

[0038] In a preferred embodiment, the power-up sequence initializes thepower control section to the non-operate mode. This is accomplished bypresenting a logic 0 to pin 2 of IC USA to mimic a current imbalancecondition.

[0039] The power-up reset pulse created by IC U5B, resistor R13,capacitor CS and diode CR8 is typically 7 msec. The reset is determinedby the time it takes to charge capacitor C5 through resistor R13 to thethreshold set by IC U5B. Diode CR8 provides a quick reset.

[0040] Referring to FIGS. 2 and 6, diodes CR1, CR2, CR3, CR4, CR5, andCR6 form a full-wave three-phase bridge. Capacitor C1 acts as thestorage device for the 281 V peak voltage produced by the bridge. Theregulator is a preferably buck-type configuration with the abnormalarchitecture of having the inductor in the lower side. This isacceptable because the circuit does not have to be referenced to earthground. In fact, the on-board electrical ground is approximately 270 Vabove earth ground.

[0041] Preferably, the switcher operates in a non-conventional mode. Ifit senses that output voltage is low, it turns on and remains on untilthe current through inductor L1 reaches a pre-determined amount.Otherwise, the cycle is skipped. Energy is stored in inductor L1 andtransferred to output capacitor C3 through diode CR7. Proper regulationis determined by Zener VR1 and opto-coupler U2. Capacitor C2 serves tostore a small amount of energy that the regulator uses to operate itsinternal circuitry.

[0042] Referring to FIGS. 9-13, illustrating an alternate preferredembodiment of a control system of the present invention adapted for anAC-DC application, to interrupt the circuit when a current imbalance issensed. As is shown in FIG. 9, the aircraft applicable current imbalancedetection and circuit interrupter 10 of the invention interrupts acircuit 20 having a line side 24 and a load side 26 with a ground fault.The load may be a motor, or any electrical device drawing a load, whereprotection of equipment or personnel is desired. The current imbalancedetection and circuit interrupter of the invention includes a powersupply 30, a sensor 40, a logic controller 50, a power controller 60,and a fault indication and reset 55. The power supply is configured toprovide power to the logic controller, and the sensor is configured tosense a current imbalance in the line side 20 of the circuit 24, and tooutput a sensor signal to the logic controller. The logic controller isconfigured to receive the relay control input signal and to receive andprocess the sensor signal input from the sensor, and the powercontroller is configured to receive input from the logic controller andremove power to the load side of the circuit when a current imbalance issensed.

[0043]FIGS. 10 and 11 illustrate a detailed view of a preferredembodiment of the power supply. FIG. 12 illustrates a detailed view of apreferred embodiment of the logic controller. Referring to FIG. 13,showing a sensor for use in the control system of the invention, in apreferred embodiment of the present invention, the sensor, which is anAmploc Pro 5 Hall effect linear sensor with an output of 233 mV/A whenoperated at 10V. All three line side wires pass through the sensor core.Kirchoff's current law states that the net current in a node is 0.Considering the wye connection point of the load side pump winding , thenet current in the phase windings, when algebraically summed, is 0. If aground fault exists, that is where the current is supplied through thesensor but does not return through the sensor, the algebraic sum of thecurrents in the phase wires would be equal to the ground fault current.

[0044] Referring to FIGS. 12, in a preferred embodiment, the output ofthe sensor is approximately one-half of the supply voltage, for nomeasured imbalance. Amplifier U3A amplifies the signal by a factor of10. The gain is set by the ratio of resistors R5 and R3. The 3 db pointis where the reactance of capacitor C4 is equal to the resistance of R5.This occurs at 3386 Hz. Resistors R1, R2, and R4 bias the amplifier andhave been selected so that a maximum value of 1 meg, for resistor R4, isrequired to adjust the amplifier output to mid supply with the sensor atits specified worse case high output. Calibration for the worse case lowoutput of the sensor is easily achieved.

[0045] Amplifiers U3B and U3C, and resistors R6, R7, and R8 are set todetect a current imbalance of 1.5±0.5 Arms. A high output from amplifierU3B or U3C indicates an imbalance is present in excess of the 1.5 Armsthreshold. IC U4A “OR's” the outputs from amplifiers U3B and U3C. Alogic 0 at its output indicates one or the other failure condition ispresent. Simultaneous imbalance inputs can be handled but are physicallynot possible since a positive imbalance cannot exist at the same time asa negative imbalance.

[0046] If a fault condition exists, it passes through IC U5A presentinga logic 1 to the latch comprised of ICs U4B and U4C. A logic 1, at pin5, forces the output pin 4 low, turning transistor Q1 off, which removesthe drive signal to the power control stage. Pin 9, the other input tothe latch, is normally at logic 0. This will cause pin 10 to go high,setting the latch by presenting a logic 1 to pin 6.

[0047] In a preferred embodiment, the power-up sequence initializes thepower control section to the non-operate mode. This is accomplished bypresenting a logic 0 to pin 2 of IC U5A to mimic a current imbalancecondition.

[0048] The power-up reset pulse created by IC U5B, resistor R13,capacitor C5 and diode CR8 is typically 7 msec. The reset is determinedby the time it takes to charge capacitor C5 through resistor R13 to thethreshold set by IC U5B. Diode CR8 provides a quick reset.

[0049] Referring to FIG. 10 and 11, diodes CR1, CR2, CR3, CR4, CR5, andCR6 form a full-wave three-phase bridge. Capacitor C1 acts as thestorage device for the 281V peak voltage produced by the bridge. Theregulators are a buck-type configuration with the abnormal architectureof having the inductor in the lower side. This is acceptable because thecircuit does not have to be referenced to earth ground. In fact, theon-board electrical ground is approximately 270V and 260V above earthground for the 10 V and 20V supplies respectively.

[0050] Preferably, the switcher operates in a non-conventional mode. Ifit is sensed that an output voltage is low, the corresponding controllerturns on and remains on until the current through inductor L1 or L1Areaches a pre-determined amount. Otherwise, the cycle is skipped. Energyis stored in inductor L1 or L1A and transferred to output capacitor C3or C3A through diode CR7 or CR7A. Proper regulation is determined byZener VR1 or VR1A and opto-coupler U2 or U2A. Capacitor C2 or C2A servesto store a small amount of energy that each respective regulator uses tooperate its internal circuitry.

[0051] Most aircraft presently in service utilize circuit breakers withthe limitations previously discussed. While the electronic andelectromechanical aspects of the present invention impart additionalprotection to the protection provided by such circuit breakers, it wouldbe desirable to be able to package the invention in a form which wouldallow ease of retrofit to existing aircraft, newly constructed and newaircraft designs, thus bringing the benefits of the invention to a widerrange of applications. Accordingly, in a further presently preferredaspect of the invention, the electronic and electromechanical elementsof the current imbalance detection and circuit interrupter are housedwithin a housing which has a similar form factor to prior art powercontrollers. The invention connects with the circuit to be monitored andcontrolled through the existing power controller electrical connector,and it draws power from the circuit to be controlled. While there arenumerous form factors which can impart additional protection to theprotection provided by such circuit breakers, one of our form factors isrelated to the power controllers used in the Boeing 757 aircraft and thelike, which have an installed height of approximately 1.78 inches abovethe mounting surface, a width of approximately 1.53 inches above themounting surface, and a total height of 3.28 inches from the top to thebottom of the electrical terminals.

[0052] With reference to FIG. 14, in one presently preferred aspect ofthe invention, each of the above described circuit configurations can beadvantageously contained in a corresponding housing 70, which istypically no more than about 3.28 inches (about 8.33 cm.) from top 72 tobottom 74, no more than about 1.53 inches (about 3.89 cm.) wide alongits front 76 and rear 78 sides, and no more than about 2.51 inches(about 6.38 cm.) from the front side 80 of the front mounting flange 82to the rear side 84 of the rear mounting flange 86. The housing alsoincludes a relay 87. Referring to FIG. 14, FIG. 15, and FIG. 16, anelectrical connector means such as the terminal block or connector plate88 is provided at the bottom of the aircraft applicable currentimbalance detection and circuit interrupter housing, typically witheight screw-type electrical connectors, A1, A2, X1, B1, B2, C1, C2, andX2, although other conventional types of wire connectors may also besuitable. Referring to FIG. 4, FIG. 8, FIG. 13 and FIG. 16, theconnectors A1 and A2 accommodate a first line and load A; the connectorsB1 and B2 accommodate a second line and load B, and the connectors C1and C2 will accommodate a third line and load C. As is shown in FIG. 15and FIG. 16, the connector plate is mounted to the housing of theaircraft applicable current imbalance detection and circuit interrupterby mounting screws 90, which extend through sleeves 92 in the housing,illustrated in FIG. 18 and FIG. 19, as is explained further below.

[0053] Referring to FIG. 17, FIG. 18 and FIG. 19, one or more circuitboards, such as a first printed circuit board 94 and a second printedcircuit board 96, for mounting the components of the above describedcircuit configurations, can be mounted within the housing with notches98 in the printed circuit boards fitting around the sleeves 92 of themounting screws 90.

[0054] From the above, it may be seen that the present inventionprovides a method and apparatus for suppressing arcs in electricalequipment in aircraft which may be adapted to a variety of systems andcomponents. As such, it provides additional reliable and rapiddisconnect of power to the existing systems, thus reducing damage fromground faults in the circuits. While a particular form of the inventionhas been illustrated and described it will also be apparent that variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited except as by the appended claims.

What is claimed is:
 1. An aircraft applicable current imbalancedetection and circuit interrupter for interrupting an electrical circuitto an electrical load, the electrical circuit having a line side and aload side, the aircraft applicable current imbalance detection andcircuit interrupter comprising: a housing, said housing furtherincluding electrical connector means for connecting to the electricalcircuit line side and load side; a power supply disposed in the housingand electrically connected to the line side of the electrical circuit; asensor disposed in the housing and configured to be powered by theelectrical circuit to be monitored for sensing a current imbalance inthe electrical circuit to be monitored and for providing a sensor signalindicating the existence of an undesirable current appearing at the loadside of the electrical circuit based on said sensing of said currentimbalance; a logic controller disposed in the housing and configured tobe powered by the electrical circuit to be monitored, to receive thesensor signal from the sensor and to output a fault signal representinga fault; and a power controller configured to receive said fault signalfrom the logic controller and to remove power to the load side of theelectrical circuit responsive to the input from the logic controller. 2.The aircraft applicable current imbalance detection and circuitinterrupter of claim 1, wherein the load comprises a motor.
 3. Theaircraft applicable current imbalance detection and circuit interrupterof claim 1, wherein said sensor comprises a Hall effect device.
 4. Theaircraft applicable current imbalance detection and circuit interrupterof claim 1, wherein the aircraft applicable current imbalance detectionand circuit interrupter receives power to operate from the electricalcircuit being monitored.
 5. The aircraft applicable current imbalancedetection and circuit interrupter of claim 1, wherein the aircraftapplicable current imbalance detection and circuit interrupterinterrupts arcing within a device being operated by the load side of theelectrical circuit.
 6. The aircraft applicable current imbalancedetection and circuit interrupter of claim 1, wherein the aircraftapplicable current imbalance detection and circuit interrupter iscontained within an envelope compatible with that of existing powercontrollers for the aircraft and using the same monitoringconfigurations.
 7. The aircraft applicable current imbalance detectionand circuit interrupter of claim 1, wherein the electrical connectormeans comprises an electrical connector plate on the housing forconnecting to the electrical circuit line side and load side of theelectrical circuit to be monitored.
 8. The aircraft applicable currentimbalance detection and circuit interrupter of claim 7, wherein saidelectrical connector plate comprises a plurality of electricalconnectors.
 9. The aircraft applicable current imbalance detection andcircuit interrupter of claim 8, wherein said electrical connector platecomprises a first pair of connectors accommodating a first load line, asecond pair of connectors accommodating a second load line, and a thirdpair of connectors accommodating a third load line.
 10. An aircraftapplicable current imbalance detection and circuit interrupter forinterrupting an electrical circuit to an electrical load, the electricalcircuit having a line side and a load side with a ground fault, theaircraft applicable current imbalance detection and circuit interrupterincluding means for sensing a current imbalance in the electricalcircuit, means for outputting a fault signal representing a fault, andmeans for removing power to the load side of the electrical circuitresponsive to the fault signal, the aircraft applicable currentimbalance detection and circuit interrupter comprising: a housing forelectrical components of the aircraft applicable current imbalancedetection and circuit interrupter, and wherein the housing includes anelectrical connector plate for connecting to the electrical circuit lineside and load side of the electrical circuit.
 11. The aircraftapplicable current imbalance detection and circuit interrupter of claim10, wherein said electrical connector plate comprises a plurality ofelectrical connectors.
 12. The aircraft applicable current imbalancedetection and circuit interrupter of claim 10, wherein said housing isno larger than a power controller to be removed from an aircraft forretrofitting of the aircraft applicable current imbalance detection andcircuit interrupter.
 13. The aircraft applicable current imbalancedetection and circuit interrupter of claim 11, wherein said bottomelectrical connector plate comprises a first pair of connectorsaccommodating a first load line, a second pair of connectorsaccommodating a second load line, and a third pair of connectorsaccommodating a third load line.
 14. An aircraft applicable currentimbalance detection and circuit interrupter for interrupting anelectrical circuit to be monitored to an electrical load, the electricalcircuit having a line side and a load side, the aircraft applicablecurrent imbalance detection and circuit interrupter including means forsensing a current imbalance in the electrical circuit, means to output afault signal representing a ground fault in the circuit being monitored,means for fault indication and fault indication reset, and means toremove power to the load side of the electrical circuit responsive tothe fault signal. The aircraft applicable current imbalance detectionand circuit interrupter comprising further: a housing having anelectrical connector means for connecting to the electrical circuit lineside and load side; a power supply disposed in the housing and connectedto the line side of the electrical circuit; a sensor disposed in thehousing and configured to be powered by the power supply for sensing acurrent imbalance in the electrical circuit and for providing a sensorsignal indicating the existence of an undesirable current imbalanceappearing at the load side of the electrical circuit based on saidsensing of said current imbalance; a logic controller disposed in thehousing and configured to be powered by the power supply, to receiveinput from the relay control signal and the sensor signal from thesensor, and to output a fault signal representing a current imbalance,and remove power to the power controller when there is currentimbalance; a direct current (DC) controlled power controller configuredto remove power to the load side of the electrical circuit whende-energized by the logic controller; a fault indicator configured toreceive said fault signal from the logic controller, to indicate acurrent imbalance condition has occurred; a reset switch to reset thefault indicator; and a form factor that packages the current imbalancedetection and circuit interrupter circuitry in a space compatible withan equivalent power controller used in the aircraft.
 15. The aircraftapplicable current imbalance detection and circuit interrupter of claim14 wherein the aircraft applicable current imbalance detection andcircuit interrupter receives the relay control signal and processes thissignal to switch on and off the power controller; and wherein the relaycontrol signal, depending on the aircraft, may be alternate current (AC)or direct current (DC).
 16. The aircraft applicable current imbalancedetection and circuit interrupter of claim 15 wherein the aircraftapplicable current imbalance detection and circuit interrupter iscapable of accepting and processing either AC or DC relay controlsignals to control a built-in DC controlled power controller.
 17. Theaircraft applicable current imbalance detection and circuit interrupterof claim 14, wherein the load comprises a motor.
 18. The aircraftapplicable current imbalance detection and circuit interrupter of claim14, wherein the aircraft applicable current imbalance detection andcircuit interrupter receives power to operate from the line side of theelectrical circuit being monitored, without requiring new aircraftwiring.
 19. The aircraft applicable current imbalance detection andcircuit interrupter of claim 14, wherein said sensor comprises a Halleffect device.
 20. The aircraft applicable current imbalance detectionand circuit interrupter of claim 14, wherein the aircraft applicablecurrent imbalance detection and circuit interrupter suppresses arcingwithin a device being operated by the electrical circuit.
 21. Theaircraft applicable current imbalance detection and circuit interrupterof claim 14, wherein the aircraft applicable current imbalance detectionand circuit interrupter discontinues ground fault conditions within adevice being operated by the electrical circuit.
 22. The aircraftapplicable current imbalance detection and circuit interrupter of claim14, wherein said aircraft applicable current imbalance detection andcircuit interrupter replaces an existing aircraft power controller. 23.The aircraft applicable current imbalance detection and circuitinterrupter of claim 14, wherein the electrical connection meanscomprises an electrical connector for connecting to the electricalcircuit line side, load side of the electrical circuit, and relaycontrol input signal.
 24. The aircraft applicable current imbalancedetection and circuit interrupter of claim 23, wherein said electricalconnector comprises a plurality of electrical connectors.
 25. Theaircraft applicable current imbalance detection and circuit interrupterof claim 24, wherein said electrical connector in one preferredembodiment comprises a first pair of connectors accommodating a firstline and load side, a second pair of connectors accommodating a secondline and load side, and a third pair of connectors accommodating a thirdline and load side, and a pair of connectors accommodating the relaycontrol input.
 26. The aircraft applicable current imbalance detectionand circuit interrupter of claim 14, wherein said housing includes atleast one circuit board mounted within the housing for mountingcomponents of the circuit.
 27. An aircraft applicable current imbalancedetection and circuit interrupter for interrupting an electrical circuitto an electrical load, the electrical circuit having a line side and aload side with a ground fault comprising: a housing having an electricalconnector means for connecting to the electrical circuit line side andload side; at least one power supply disposed in the housing andconnected to the line side of the electrical circuit; a sensor disposedin the housing and configured to be powered by one of the power suppliesfor sensing a current imbalance in the electrical circuit and forproviding a sensor signal indicating the existence of an undesirablecurrent imbalance appearing at the load side of the electrical circuitbased on said sensing of said current imbalance; a logic controllerdisposed in the housing and configured to be powered by one of the powersupplies, to receive input from the relay control signal and the sensorsignal from the sensor, and to output a fault signal representing acurrent imbalance, and to interrupt the relay control signal when thereis a current imbalance; a power controller configured to be energized bythe relay control signal and to remove power to the load side of theelectrical circuit when the relay control signal is interrupted; and afault indicator configured to receive said fault signal from the logiccontroller, to illuminate indicating a current imbalance condition hasoccurred; and a reset switch to reset the fault indicator.
 28. Theaircraft applicable current imbalance detection and circuit interrupterof claim 27 wherein said sensor comprises a Hall effect device.
 29. Theaircraft applicable current imbalance detection and circuit interrupterof claim 27 wherein said sensor comprises a transformer connected to theload side of the circuit.
 30. The aircraft applicable current imbalancedetection and circuit interrupter of claim 27 wherein the aircraftapplicable current imbalance detection and circuit interrupter receivesthe relay control signal to directly power the power controller andwherein the relay control signal, depending on the aircraft, may bealternate current (AC) or direct current (DC); and whereby the type ofpower controller built-in with the current imbalance detection andcircuit interrupter shall correspond to the AC or DC relay controlsignal.
 31. The aircraft applicable current imbalance detection andcircuit interrupter of claim 27, wherein the load comprises a motor. 32.The aircraft applicable current imbalance detection and circuitinterrupter of claim 27, wherein the aircraft applicable currentimbalance detection and circuit interrupter receives power to operatefrom the line side of the electrical circuit being monitored, withoutrequiring new aircraft wiring.
 33. The aircraft applicable currentimbalance detection and circuit interrupter of claim 27, wherein theaircraft applicable current imbalance detection and circuit interrupterdiscontinues arcing within a device being operated by the electricalcircuit.
 34. The aircraft applicable current imbalance detection andcircuit interrupter of claim 27, wherein the aircraft applicable currentimbalance detection and circuit interrupter discontinues ground faultconditions within a device being operated by the electrical circuit. 35.The aircraft applicable current imbalance detection and circuitinterrupter of claim 27, wherein the electrical connection meanscomprises an electrical connector for connecting to the electricalcircuit line side, load side of the electrical circuit, and relaycontrol input signal.
 36. The aircraft applicable current imbalancedetection and circuit interrupter of claim 27, wherein said electricalconnector comprises a plurality of electrical connectors.
 37. A methodfor operating an aircraft applicable current imbalance detection andcircuit interruption system comprising: monitoring at least oneelectrical field generated by current in a line to be monitored leadingto a load to be controlled by said system; detecting a current imbalanceon the basis of differences between said electrical field and apredetermined value; powering the means for monitoring and detectingfrom the electrical line being monitored; generating a control signalwherein the sensor detects an electrical field which is different fromsaid predetermined value by a predetermined amount; and using saidcontrol signal to actuate a DC relay which removes power from the loadbeing monitored.
 38. The method of claim 37, wherein said monitoringmeans further includes the step of monitoring said electrical field witha Hall effect sensor.
 39. The method of claim 37, further comprising thestep of: housing the aircraft applicable current imbalance detection andcircuit interrupter system in a housing which is mechanically andelectrically substitutable for an existing aircraft power control relay.